feat(Core/Player): PartyLevelReq invite settings (#1919)

- Minimum level at which players can invite to group setting

src/server/worldserver/worldserver.conf.dist

@@ -1973,6 +1973,15 @@ ChatLevelReq.Whisper = 1
 
 ChatLevelReq.Say = 1
 
+#
+#    PartyLevelReq
+#        Description: Minimum level at which players can invite to group, even if they aren't on
+#                     the invite friends list. (Players who are on that friend list can always
+#                     invite despite having lower level)
+#        Default:     1
+
+PartyLevelReq = 1
+
 #
 #    AllowPlayerCommands
 #        Description: Allow players to use commands.